Study On Surface Thermal Environment Of Xuzhou City Based On Spatial Planning

With the acceleration of the urbanization process,urban space is spreading rapidly,and the urban thermal environment is continuously deteriorating.The development and utilization of urban space is an important factor affecting the urban thermal environment,and spatial planning,as a policy transmission tool for urban space development and utilization,plays a vital role in the regulation of the thermal environment.Therefore,a comprehensive and systematic understanding of the mechanism of spatial planning factors on the spatiotemporal heterogeneity of urban thermal environment and the guidance of safe and comfortable thermal environment pattern by means of spatial planning are very important for promoting the construction of high-quality urban living environment and the sustainable and healthy development of the city.This research takes Xuzhou,a typical resource-based city with rapid urbanization,large-scale spatial expansion,and prominent thermal environment problems as the research object,takes the main urban area as the research scope,comprehensively considers the typical phases after urbanization recovery and growth and the thermal environment evolution phase to determine the research cycle,based on the data of urban space development and utilization,combined with the spatial planning system,sorts out spatial planning factors hierarchically and systematically,describes the evolution characteristics of urban space development and utilization,and uses single-window algorithm to extract surface thermal environment information through Landsat remote sensing image data,explores the temporal and spatial differentiation of thermal environment,and uses classical statistical analysis and geography Weighted regression analysis and other methods quantitatively explore the space-time effects of spatial planning factors on the thermal environment.At the same time,combined with my country's current spatial planning system,a spatial planning coordination framework based on thermal environment optimization is constructed,and a spatial planning strategy for urban thermal environment optimization is further proposed.The results as follows:(1)The basic theoretical framework of urban thermal environment research based on spatial planning is constructed.The content of the theoretical framework involves the basic theory,connotation,content,principle,target system,method path and planning response,etc.,and from the four basic levels of urban space expansion,urban network structure,construction land layout,and plot development and construction,an index system for the thermal environment action mechanism of spatial planning factors has been established.(2)The characteristics of urban space development and utilization in the main urban area of Xuzhou in the past 25 years are summarized:(1)Urban construction land shows an obvious sprawling expansion pattern.The expansion intensity of construction land shows a trend from fluctuations to overall stability.The urban spatial profile is relatively complex but not compact enough.The overall shape of the city embodies the evolution from a star to a rectangle.(2)The road network in the main urban area is constantly improving.The road network structure developed into a multi-center dense road network structure and then evolved to spatial homogenization.The betweenness centrality of the road network reflects the distribution characteristics of typical planar clusters extending in the axial direction,the direct accessibility of the road network reflects a clear group structure,and the proximity of the road network reflects a clear layered structure.(3)The scale of ecological source area is showing a downward trend,and the ecological network coverage is relatively poor.(4)The expansion of urban construction land reflects the characteristics of extension,and the area of high development intensity reflects the evolution of the characteristics of spatial aggregation,axial expansion,and extension to the whole area.The green coverage of construction land parcels is increasing,and it extends from the old city to the whole area.(3)The evolution characteristics of surface thermal environment in the main urban area of Xuzhou in the past 25 years are analyzed as follows:(1)Over the years,the surface temperature has shown obvious spatial differentiation.The old city,Tongshan area and the northern industrial area are obvious high temperature areas.The water surface of Yunlong Lake,spring mountains and other mountains,and the fringe area of the main urban area are low temperature areas.(2)The proportion of high-temperature areas in the main urban area has shown a downward trend,and the intensity of the heat island has shown an increasing trend over the years.(3)The spatial distribution characteristics of heat island region show three typical stages: the stage of local point relative concentration distribution(1995),the stage of expanding distribution along the urban construction land line(1998,2003,2004),and the stage of area aggregation and overall homogeneous coverage(2010-2019).(4)The main types of construction land affecting the positive and negative effects of urban thermal environment are manufacturing land,logistics and storage land,commercial and business facilities land,residential land,green space and water system.The overall order is logistics and storage land,manufacturing land,commercial service land and residential land commercial and business facilities land,residential land,street and transportation land,administration and public services land,municipal utilities land,green space and square land.(4)The mechanism of spatial planning factors on the spatial heterogeneity of thermal environment is explored quantitatively:(1)The expansion of urban space has a relatively direct impact on the urban thermal environment.The higher the complexity of the urban morphology,the lower the intensity of the urban heat island effect;for every square kilometer of construction land,the intensity of the urban heat island will increase by 0.062°C.(2)The characteristics of urban road structure,network centrality and road environment construction are important factors that affect the thermal environment of urban roads.The betweenness centrality and proximity of the road have little influence on the thermal environment.The green coverage rate of roads basically reflects the obvious negative effect of global thermal environment,while the direct,width,length and other factors have significant directional differences due to the different spatial location.(3)Ecological network is the low-lying space of regional temperature,and it is an important cold source structure in the process of urban thermal environment improvement.The thermal environment effect threshold of ecological source is 300-500 meters,and the thermal environment effect threshold of ecological corridor is 400-500 meters.Among them,the distance threshold of the most effective cooling stage of ecological source and ecological corridor is 100 m and 60 m respectively.(4)Over the years,the patch of heat island in the study area presents the spatial characteristics from local area coverage to global scattered distribution,and the coverage area basically presents the expansion trend.The manufacturing and logistics concentration area with railway marshalling yard as the core area is the most important patch to maintain the urban thermal landscape pattern,and the key to break the urban thermal landscape pattern.(5)The green coverage of construction land has a weak spatial sensitivity to the thermal environment,and the degree of impact on the thermal environment of the plot basically presents a more obvious ring structure,while the impact of NDBI on the thermal environment shows a strong spatial heterogeneity.(5)The hierarchical and systematic spatial planning strategies to improve the thermal environment are proposed as follows:(1)The coordination framework of dynamic adaptability of urban spatial planning based on thermal environment improvement is defined.The principles of overall control and local policy for thermal environment improvement are determined.The implementation of urban form control and reasonable and effective allocation of land resources,implement the spatial heterogeneity control of urban spatial structure thermal environment based on centrality and threshold effect at the spatial structure level,in the level of land layout,the implementation of thermal pattern improvement,in the level of development and construction,focusing on the improvement of thermal environment of high-temperature plots.(2)Propose specific spatial planning strategies for thermal environment improvement from the aspects of urban scale and form control,land resource allocation,road network organization,ecological network improvement,land use layout optimization,and development and construction guidance.